title: Positive and negative regulation of Easter, a member of the serine protease family that controls dorsal-ventral patterning in the Drosophila embryo.
abstract: The sequential activities of four members of the trypsin family of extracellular serine proteases are required for the production of the ventrally localized ligand that organizes the dorsal-ventral pattern of the Drosophila embryo. The last protease in this sequence is encoded by easter, which is a candidate to activate proteolytically the ligand encoded by spätzle. Here, we demonstrate biochemically that the zymogen form of Easter is processed in vivo by a proteolytic cleavage event that requires the three upstream proteases. Processed Easter is present in extremely low amounts in the early embryo because it is rapidly converted into a high molecular mass complex, which may contain a protease inhibitor. Easter zymogen activation is also controlled by a negative feedback loop from Dorsal, the transcription factor at the end of the signaling pathway. Each of these regulated biochemical processes is likely to be important in generating the ventral-to-dorsal gradient of Dorsal protein that organizes cell fates in the early embryo.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: S
authors.initials: S
authors.lastname: Misra
authors.forename: P
authors.initials: P
authors.lastname: Hecht
authors.forename: R
authors.initials: R
authors.lastname: Maeda
authors.forename: K V
authors.initials: KV
authors.lastname: Anderson
mesh_terms: D000818:Animals; D004330:Drosophila / Q000196:embryology* / Q000254:growth & development; D029721:Drosophila Proteins; D004789:Enzyme Activation / Q000502:physiology; D004792:Enzyme Precursors / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D017344:Genes, Insect / Q000235:genetics; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins / Q000032:analysis; D011480:Protease Inhibitors / Q000494:pharmacology; D011487:Protein Conformation; D012697:Serine Endopeptidases / Q000502:physiology*; D014157:Transcription Factors; D051879:Twist-Related Protein 1
chemical_list: D029721:Drosophila Proteins; D004792:Enzyme Precursors; D019476:Insect Proteins; D009687:Nuclear Proteins; D011480:Protease Inhibitors; D014157:Transcription Factors; D051879:Twist-Related Protein 1; C086179:spz protein, Drosophila; D012697:Serine Endopeptidases